In many areas involving fluid-flow, it is desirable to combine two streams of fluid that have different pressures. An example of such a system is a well that produces natural gas.
The gas that comes from a flowing well is typically passed through a separator where liquids “drop out” of the gas stream. Those liquids are very valuable; they contain a high BTU content. The liquids are removed from the separator and placed in a large liquid storage tank, and the remaining gas is removed from the separator in a gas line. The liquid storage tank generates vapor that is slightly above atmospheric pressure. That vapor must be compressed to a pressure closer to the gas leaving the separator (which is expensive) or that vapor must be vented to the atmosphere. In some cases, the volume of vapor is sufficient that a flare can be used; however, flaring of the vapor usually results in incomplete combustion and undesirable by-products, and that results in pollution. It is also a waste of the energy content of the vapor.
Therefore, there is a need for a method, system, and device, which can take fluid of a first pressure (for example, high pressure gas coming from a separator) and combine into that first-pressure-fluid a second fluid of lower pressure (for example, the vapor from a liquid storage tank) while avoiding the normal costs of compression of the second, lower pressure gas.
In some other examples, there are multiple wells in an oil and/or gas producing field. Those wells may be producing gas at differing pressures. To put those multiple wells (each producing at a different pressure) on an individual gas transmission line requires pressure release from the higher pressure flows or compression of the lower line pressure flows. Again, the cost of compression is high; either an electric or gas-fired engine driven compressor is needed. Whether the cost is in lost gas, the cost of electricity, or the cost of the fuel needed to run the compressor, it is undesirable. Therefore, there is a need to combine flows of fluids having different pressures into an individual fluid flow line without the traditional compression or pumping steps.